1. Technical Field
The present invention relates to an actuator, an optical scanner and an image forming apparatus.
2. Related Art
As an example of optical scanners used for, for example, laser printers, there is known one, which employs a structure having a torsional resonator, which is manufactured by processing a Si substrate with a micromachining technique. The optical scanner employing such the structure can advantageously perform light scanning at higher velocity than one employing a polygon mirror.
The actuator as disclosed in, for example, JP-A-2004-191953, has a plate-shaped reflecting mirror, which is supported from either side by a pair of spring portions. The respective spring portion branches off halfway, and a piezoelectric body is provided at each of the bifurcation. In the case of the actuator thus constructed, voltage is applied to the each of the piezoelectric bodies so as to bend the respective bifurcations to be deformed, thereby allowing the reflecting mirror to rotate while twisting the pair of spring portions as a whole to be deformed.
In the case of such the actuator, the mirror is allowed to rotate only about one axis extending along the one pair of spring portions as the center axis of rotation. Therefore, when such the actuator is used as an optical scanner, light can be irradiated either in the direction of main scanning or in the direction of sub-scanning. Accordingly, in order to perform both the main scanning and the sub-scanning, two actuator of this type must be used, which disadvantageously involving increase in cost and growth in size.